For those who've been pining for a personal jetpack, there may soon be more than one to choose from.

The Martin Aircraft company and Jetlev Technologies have each announced plans to manufacture separate versions of the long-awaited flying machine. Martin Aircraft has set a tentative deadline of December to start filling orders for as many as 2,500 customers on their waiting list. Jetlev technologies has stated that they've begun manufacturing a batch of 20 packs and will start selling them as early as mid-May, according to Popular Mechanics.

While both machines are being marketed as Jetpacks, they aren't so in the truest sense since neither uses jet or rocket-powered technology. The original jetpack concepts, which soared in popularity in the 1950's, were born out of attempts by the U.S. Army to produce a rocket pack that enabled soldiers to manuever in the air as they took part in reconnaissance missions.

An early 1952 prototype allowed a person to stay airborne for what was at the time an impressive few seconds. But after a series of negligible improvements, such as the Bell Rocket Belt that had a slightly better flight time and speeds of up to 10 mph, the army dropped the project altogether after coming to the conclusion that the jetpacks were too costly and riddled with too many drawbacks to be feasible.

A few companies have since tried their hands at developing a commercial jetpack -- but with less than stellar results. For instance, the company JetPack International sells a jetpack that provides enough thrust for about 30 seconds of air travel. The latest inventions from Martin Aircaft and Jetlev marks a real departure from previous these less practical prototypes in that they offer the operator the ability to fly for a much lengthier period of time.

So how did they do it? Well, here's a breakdown of the technology that may be useful for you comparison shoppers out there.

The Jetlev Jetpack

creates thrust by blasting water from its nozzles. The water is supplied through a 33-foot-long hose connected to a watercraft

powered by a 225 horsepower motor that shoots water at 1,000 gallons per minute

Contributing Editor
Tuan C. Nguyen is a freelance science journalist based in New York City. He has written for the U.S. News and World Report, Fox News, MSNBC, ABC News, AOL, Yahoo! News and LiveScience. Formerly, he was reporter and producer for the technology section of ABCNews.com. He holds degrees from the University of California...
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